The place of the Neanderthals in hominin phylogeny

• There are many valid definitions of species, all with their own advantages.
• Hybridisation is a regular occurrence despite long periods of genetic isolation.
• There is no strong morphological evidence for hybrid specimens.
• Morphological evidence supports separate species status for H. neanderthalensis.

Debate over the taxonomic status of the Neanderthals has been incessant since the initial discovery of the type specimens, with some arguing they should be included within our species (i.e. Homo sapiens neanderthalensis) and others believing them to be different enough to constitute their own species (Homo neanderthalensis). This synthesis addresses the process of speciation as well as incorporating information on the differences between species and subspecies, and the criteria used for discriminating between the two. It also analyses the evidence for Neanderthal–AMH hybrids, and their relevance to the species debate, before discussing morphological and genetic evidence relevant to the Neanderthal taxonomic debate. The main conclusion is that Neanderthals fulfil all major requirements for species status. The extent of interbreeding between the two populations is still highly debated, and is irrelevant to the issue at hand, as the Biological Species Concept allows for an expected amount of interbreeding between species.